My sister's P-kid (adult, with severe depression, cognitive issues, bi-polar; who also went through multiple lyme infections) saw Dr T. They did a series of expensive tests that showed infections, which they treated. His condition improved some then deteriorated. He then did more genetic testing which netted nothing. They were disappointed and dropped him without pursuing further treatment. As far as I know he advocates IVIG but I have not read of many patients of his who have done PEX or Rituximab. If others have seen any contradictory information please correct me - there are some very devoted patients of his who may know better.
We have used Dr L. She treats traditional strep mediated PANDAS but is open to PANS, although she herself will not treat other infections. If you use her I would also get Lymes and coinfection test as well other PANS drivers. Dr L is great.